I dont know how others are using the filter options, but I use the specifications as filter options, but this means I have to create two almost similar lists.
So I think it would be very handy when creating specifications in the specifications manager if you can tick a checkbox if you want to use a specification as a Filter option. This way you only have to create one list that is used as specifications and for defining Filters.

Also I’d like to group certain results together when people compare products. Basically these groups are the same as those of the specifications. So in stead of browsing through one long list, you can easily lookup the group you are most interested in.

Perhaps it is also an interesting idea to have those specifications that differ between products listed on top of the specifications in a comparison. That way you can see directly on which points the products in the comparison chart differ, because these specifications are listed in a separate group on top.